TW561131B - Micro-electromechanical system and its fabricating method - Google Patents

Abstract

A cantilever beam type micro-electromechanical system (MEMS) is formed on a substrate. Two first electrodes are formed in a first dielectric layer on the substrate and a waveguide line is formed between the first electrodes. A patterned sacrificial layer and an arm layer are formed on the substrate. Two second electrodes and a second dielectric layer are formed in the arm layer, and an optical grating is formed in the second dielectric layer. Finally, a cap layer is formed on the substrate, and the patterned sacrificial layer is removed.

Description

561131 V. Description of the invention α) Technical field to which the invention belongs The present invention provides a method for manufacturing a micro-electromechanical system (MEMS), especially a cantilever beam (cant i lever be am) used in the field of optical fiber communication ) Type micro-electro-mechanical system manufacturing method. In the past, with the increasing popularity of the Internet and the rapid growth of high transmission capacity, in order to solve the network congestion situation, cable modems (cabl (modem), asynchronous digital subscriber loop (ADSL), and time multiplexing have been proposed successively. Solutions such as dense wavelength-division multiplexing (DWDM) combined with wavelength multiplexing. Among them, the DWDM system has the ability to use multiple wavelengths of optical signals in a single fiber at the same time, making the fiber network The advantage of a large increase in channel capacity has become one of the most important optical fiber communication architectures at present. A complete DWDM optical fiber system includes optical transmitter / receiver, wavelength multiplexer / demultiplexer, fiber amplifier (EDFA), Wavelength acquisition multiplexers, dispersion compensation devices, filters, optical switch routers and other optical communication components, processing circuits and structures of optical systems, etc. In the field of optical fiber communications, the technology for making high-density wavelength multiplexers can be divided Optical filter type, fiber grating type, fiber coupler and optical waveguide type etc. Among them, optical filter

561131 V. Description of the invention (2) The chip mainly uses prism or thin film filter (TFF), and the fiber grating mainly uses various gratings, such as Fiber Bragg Grating (FBG) ) Or arrayed waveguide grating (AWG), etc., and the optical fiber coupler mainly uses various interferometers (such as Fabry-Perot Interferometer, Mach-Zehnder) and other physical mechanisms to achieve optical multi-channel filtering and beam splitting purpose. It should be from 8 wavelengths to 64 wavelengths. Actually, the thickness of the thin film is strict before about 32 wavelengths. Therefore, the current technology of using filters as waveguide gratings is poor: in view of the possibility of replacing filters In other words, it is suitable for long-distance calls on a local network. In addition, the filter that is manufactured by the most popular thermal splitter technology, which has the lowest thermal stability and low cost, is mainly used in the future, and it has become the mainstream in the market. Low-cost fiber couplers can only reach fiber optic gratings and optical waveguides to reach communication networks, while optical filter technology is evaluated prospectively and objectively, but because its optical requirements are extremely expensive, it still cannot be completely replaced. 'However, the array surface optical waveguide method similar to the semiconductor process has a growing demand for coupling the required waves, and this micro-electro-mechanical system combining optical, mechanical and electrical manufacturing will be extremely light. That is, the structure of the light-optical layer 'and because of the micro-electromechanical and electrical structure, the structure allows the characteristics of the micro-electro-mechanical system and the use of semiconductor processes to ensure the transmission during the data transfer process. It is not necessary to switch to electronic information technology. Manufacturing adjustable optical fiber communication and wireless RF communication

561131 V. Description of invention (3) It has been paid much attention. Therefore, with the rapid growth of optical fiber communication, the use of micro-electro-mechanical process technology has successfully cut into the market of optical communication components, and at the same time, DWDM systems have gradually replaced the optical-electrical-optical switching components of the optical-electrical-optical conversion process that delay the entire broadband communication system. Rong Neiming ’s micro-beam arm suspension of the machine • ft is a mainstay of supply and supply. The Mingfa issuer's original system is simple and simplified. In the footwork, the method is to produce a system of supply and system. ^, ^ The micro-mechanism of the machine is the main beam of the secondary arm. Yu Dangtong uses a series of electric power generation machines to make micro-supply for use. The only way to do it is to use the same method as the wave filter system 1. The Tongming electric multi-function machine is based on micro-advance The preferred embodiment of the present invention discloses a method for manufacturing a cantilever beam type micro-electromechanical system (MEMS). The cantilever type micro-electromechanical system is fabricated on a semiconductor substrate, and the The surface of the semiconductor substrate includes a heavily doped layer and a first dielectric layer. First, at least two first conductors are formed in the first dielectric layer to reach the surface of the heavily doped layer, and then in the first dielectric layer,

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561131 V. Description of the invention (4) A dielectric layer is formed in the first dielectric layer between the first conductors and the like. The second dielectric layer does not contact the surface of the heavily doped layer, and then is formed on the semiconductor-patterning. The sacrificial layer 'covers the second dielectric J-bottom dielectric layer and each of the first conductors, and then forms a second dielectric layer on the semiconductor substrate to cover the patterned sacrificial layer, and then the first sacrificial layer. % Layer = -the fourth dielectric layer, and the fourth dielectric layer does not contact the surface of the electric sacrificial layer, and then at least two crystalline materials are formed on the surface of the third dielectric layer, and each of the second conductive systems They are respectively located above the first conductor on both sides of the second dielectric layer, and finally the fourth dielectric layer is etched to form a plurality of openings in the electric layers, and form a first on the semiconductor substrate. After the four cap layers cover each of the second conductors, the fourth dielectric layer covers the dielectric layer, and then the patterned sacrificial layer is removed. The third time, it is not confidential and it is so small and high that it is used as an operational power system. It can be used outside the light beam to split the light. The production process of light and the combination of this and a small junction to produce a pole junction filter system requires a low level of system control. The short circuit and multi-conductor operation of the whole body is more semi-systematic than the machine. If the amount of time is small, it should be reversed with a large inch when the amount is small. It is beneficial and the product is less than the simple method. Compared with the multi-equipment system, which can produce a long-term system, the wave-consumption system only uses electricity, but the implementation mode

561131 V. Description of the invention (5) It can be applied to a P-type semiconductor substrate, an epitaxial silicon substrate or a silicon composite insulating substrate. Please refer to FIG. 1 to FIG. 13. FIG. 1 to FIG. 13 are schematic diagrams of a method for manufacturing the cantilever beam type micro-electromechanical system 10 of the present invention, in which FIG. 2 is a schematic cross-sectional structure diagram along line I-I 'in FIG. 1, FIG. 4 and FIG. It is a schematic diagram of the cross-sectional structure along the line 丨 丨 --J, in FIG. 3, and FIG. 8 is a schematic cross-sectional structure along the line III-III, in FIG.

As shown in FIG. 1 and FIG. 2, an ion implantation process is first performed, and a conformation (^ 1103 0 05 6 1 ′) ion is implanted into a meso-semiconductor substrate 12 to form a surface on the surface of the semiconductor substrate 12. The N-type heavily doped layer 14 is subjected to a rapid thermal annealing (RTA) process to repair the surface structure of the semiconductor substrate 12. Next, a thicker oxide layer 16 is deposited on the heavily doped layer 4 and then a photoresist layer (not shown in FIGS. 1 and 2) is coated on the oxide layer 16 and a lithography is used. And etch process (ph〇t〇1 丨 th〇graphy etching process (PEP)) to remove the oxide layer 16 'that is not covered by the photoresist layer to form at least two heavily-doped layers in the oxide layer 丨4 的 面 口 1 8. Then, the photoresist layer is removed, and an N-type heavily doped polycrystalline silicon layer (not shown in FIGS. 1 and 2) is deposited on the semiconductor substrate 2 and the polycrystalline silicon layer is filled into the opening 18, and then a chemical mechanical process is performed. Grinding Interview

A chemical mechanical polishing (CMp) process or an etching back process removes the polycrystalline silicon layer on the oxide layer 16 so that at least two electrodes 20 are formed in the oxide layer 16. Next, another photoresist layer (not shown in FIGS. 1 and 2) is formed on the semiconductor substrate 12, and a photolithography and etching process is used to remove the oxide layer that is not covered by the photoresist layer.

561131 V. Description of the invention (6) | A trench 22 is formed in the oxide layer 16 between the electrodes 20 and does not reach the surface of the heavily doped layer. After removing the photoresist layer, an oxide layer (not shown in FIGS. 1 and 2) is deposited on the semiconductor substrate 12 and the trench 22 is filled. Then, a chemical mechanical polishing process is performed to remove the electrode 20 and the oxide layer 16 The above | this oxide layer forms an optical waveguide line (waVegUide) 24 in the oxide layer 丨 6. Among them, the oxide layer 16 and the optical waveguide line have different emissivity: and shape. The material of the electrode 20 may include gold (goid, Au), copper (copper, Cu), and alumina (al ㈣). hum,

Al), aluminum copper (Ab Cu alloy) or other conductive materials.丨 In order to perform a chemical vapor deposition (CVD) process in I, the thickness is about 3 micrometers * (micr_ter, shown in Fig. 3), and then coated on the sacrificial layer-light ^ To form-pattern the sacrificial layer and the oxide layer U. : Remove the optical bifurcated f optical waveguide line electrode 012-deposited after a large thickness of St: layer, and then perform an oxidation layer on the semiconductor base layer 28 = = = layer 26, and the oxygen and patterned sacrificial layer & I represents about $, so that the upper surface U of the oxide layer 28 and the oxide layer 28 are formed together, and then the patterned sacrificial layer is formed to form a two-meter oxide layer 30 of the sacrificial layer. its

Ho :) I :, organic polymer or porous stone (—_) and the gasification layer 28 is used as the cantilever type microcomputer of the present invention. Page 10 561131 V. Description of the invention (7) 2 ί ί 疋The pillar (anChor) structure is mainly formed on a semiconductor substrate formed subsequently to prevent the microstructure from being affected during the subsequent removal of the patterned sacrificial layer 26.

As shown in Figure 4, a photoresist layer is then coated on the oxide layer 30 (not shown in Figure 4), and a lithography and etching process is performed to remove the oxide layer that is not covered by the photoresist layer. 30, in order to form a trench 36 on the surface of the unpatterned patterned sacrificial layer 26 in the oxide layer 30, and then use a deposition process and a mechanical polishing process to form a filled trench in the oxide layer 30 The oxide layer 38 of 36, and the upper surface of the oxide layer 38 is approximately aligned with the upper surface of the oxide layer 30. Then, a metal layer and a photoresist layer (not shown in FIG. 4) with a thickness of ~ 0.8 μm are formed on the oxide layer 30, and a photolithography and #etching process is performed to remove the unresisted photoresist. A metal layer covered by the layer to form at least two electrodes 40, and the electrodes 40 are respectively located above the electrodes 20 on both sides of the optical waveguide line 24, and then the photoresist layer is removed. The oxide layer 30 and the oxide layer 38 have different refractive indices, and the material forming the electrode 40 may include gold (Au), tungsten (Tungsten (FF)), copper (Copper, Cu), and aluminum (aluminum). , Al), I-Cu alloy (ai-Cu alloy), polycrystalline stone 戋 other conductive materials. < Then, as shown in FIG. 5, another photoresist layer 橹 (not shown in FIG. 5) is formed on the semiconductor substrate 2 and a lithography and etching process is performed to remove the photoresist layer. The covered oxide layer 38 is used to form a plurality of openings 4 2 having equal pitch, 4 width and equal depth in the oxide layer 3 8 for the oxide layer 3 8 561131 V. Description of the invention (8) Let the grating be formed ( optical grating), and then a cap layer 44 is formed on the semiconductor substrate 12, and the cap layer 44 covers the opening 42, the electrode 40, the oxide layer 38, and the oxide layer 30. The depth of the opening 42 is about 1.5 micrometers, and the cap layer 44 is an oxide layer. As shown in FIGS. 6 and 7, a circular photoresist layer (not shown in FIGS. 6 and 7) is formed on the semiconductor substrate 2 and a dry etching process is performed to remove the uncovered photoresist layer. The capping layer 44 and the oxide layer 30.

At least one etch window 46 is formed in the oxide layer 30. The etch window 46 = several miles depends on the size of the micro-electromechanical system and the subsequent etching rate. Then a structure releasing process is performed. For example, the process of engraving the wet surname with the two ϊηϊ t liS trOPiC), cantilever type micro-electro-mechanical system 蚀刻 etching solution t, so that the etching solution can be uniformly etched through the etching window 46 quickly and laterally etch the patterned sacrificial layer below it 'further The reduced structure layer can be etched or corroded during the removal of the over-red pattern, so that the shape is a rislng) and the drying process is performed in order to = 2 2

The ionic bond and other forces are greater than the microstructure's back; the table & electrostatic force or the structure and the semiconductor substrate 12 such as when the spring force ', so that the micro-electro-mechanical system 10 operating efficiently, too i ^^ stlctlon) phenomenon, Τ ^ (burap) (A; V ^ ^ ^ ^ 30 ^ Low microstructure and semiconductor Λ i 2 ^ are not shown in the figure /, to figure 8), to reduce the contact area of the isomorphic substrate 12 to improve the adhesion. 561131 V. Description of the invention (9) It is worth noting that the second embodiment of the present invention shown in FIG. 9 is a cantilever-type micro-electro-mechanical system according to the present invention. Before forming the patterned sacrificial layer 2 6: An additional adhesive (glue: ^ 32) is formed on the oxide layer 16, and the adhesive layer 32 covers the oxide layer 16, the electrode 20, and the optical waveguide 24, and is used to add a patterned sacrificial layer 26 and the oxide layer 16 After forming the patterned sacrificial layer 26, a barrier (Mock) on the oxide layer 16 is formed. 3 ′ 3 ′ is used to cover the patterned sacrificial layer 2 6 to avoid subsequent process damage. Figure: ^ sacrificial layer 26 affects. Among them, the adhesive layer 32 and the barrier layer 34 can be seen, and it is necessary to prepare only one or two layers, and the formed adhesive layer 32 and the barrier layer 34 can also be selected. When the patterned sacrificial layer 26 is removed, it is removed together, as shown in Fig. 10 and Fig. 11. In addition, as shown in Fig. 12, the cantilevered micro-electromechanical system of the present invention is absolutely zero. Before the oxide layer 38 is formed, it is first formed in the oxide layer 30: its formation method is prior to the oxidation 30, at least two openings are formed (not shown in FIG. 12), and then a conductive layer is deposited on the semiconductor substrate 12 (shown in FIG. 12), and the conductive layer is filled into the two openings. Then, a chemical mechanical polishing process is used to make the upper surface of the conductive layer and the upper surface of the emulsified layer 30 approximately aligned to form the two electrodes 40. 3. The cantilevered micro-electromechanical system 10 of the present invention is mainly used in the optical fiber communication field, and is used as an optical switching element to perform filtering or light splitting. Therefore, there is a light wave at the forefront of the optical waveguide line 24. Input or output

Page 13 561131 V. Fixture of the invention (ίο) end (not shown in the figure) When the optical fiber input end of line 2 4 is applied, an electrostatic force will be generated to close the upper and lower electrodes to change the height of the hole 48, as shown in Figure 13. The tunable function of the electrical system 10 is different from that of the surrounding oxide layer 16. When the light wave reaches the grating port 42 for beam splitting and is reflected to couple out the required light wave, it will return to the place via the optical waveguide line 24 The function that requires a wavelength of light can output multiple wavelengths separately. When the multi-wavelength signal is shown by a voltage between 20 and 40, and when the multi-wavelength light wave region, the light output end of the light wavelength ^, to reach the signal, for example, the distance reaches the long wire wave, and After introducing the original as 12 volts away, the cantilever beam wave 24 will be mixed with the optical waveguide characteristics after the grating, and then the grating will be mixed with the optical waveguide first. In other words, the invention cantilever beam type micro-electro-mechanical system applied to optics has the following advantages: (1) because the light itself has no mass, only a small amount of energy can be used to drive the micro-electro-mechanical system; (2) for light, A small displacement (distance close to the wavelength) can have a significant effect on the physical phenomena of light waves and their characteristics (wavelength, light intensity, phase, etc.). (3) Micro-electromechanical systems with small dimensions have the characteristics of rapid response and rapid movement. (4) If it is not necessary to make direct contact with the environment, it has the characteristics of easy packaging. (5) Extensive use of existing semiconductor process equipment and technology can produce a large number of stable quality products. Micro-electro-mechanical systems not only have the potential to reduce overall costs, but also have high commercial feasibility. The above are only the preferred embodiments of the present invention.

Page 14 561131 V. Description of the invention (11) Equal changes and modifications made to the scope of the patent shall all fall within the scope of the invention patent. Page 15 561131 Brief description of the drawings Brief description of the drawings Figures 1 to 13 are schematic diagrams of a method for manufacturing a cantilever type microcomputer electrical system according to the preferred embodiment of the present invention. Description of Symbols 10 Cantilever MEMS 12 Semiconductor substrate 14 Heavyly doped layer 16 Oxidation layer 18 Opening 20 Electrode 22 Trench 24 Optical waveguide 26 Patterned sacrificial layer 28 Oxidation layer 30 Oxidation layer 32 Adhesive layer 34 Barrier layer 36 trench 38 oxide layer 40 electrode 42 opening 44 cap layer 46 etching window

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Claims (1)

561131 Six 'application patent scope 1. A method for manufacturing a cantilever beam type micro-electromechanical system (MEMS) The manufacturing method includes the following steps: +' Provide a semiconductor substrate, and the surface of the semiconductor substrate Including a doped layer and a first dielectric layer; forming at least two conductors in the first dielectric layer that reach the surface of the heavily doped layer; in the first conductors A second dielectric layer is formed in the first dielectric layer, and the second dielectric layer does not contact the surface of the heavily doped layer. A patterned sacrificial layer is formed on the semiconductor substrate and covers the second dielectric layer. A dielectric layer, the first dielectric layer, and each of the first conductors; "a third dielectric layer is formed on the semiconductor substrate and covers the sacrificial layer; and the fourth dielectric is on the third A fourth dielectric layer is formed in the dielectric layer without contacting the surface of the patterned sacrificial layer. Each of the second dielectric layers is formed on the surface of the third dielectric layer. At least two second conductive systems are located on the second. $ On both sides of the dielectric layer g a $ & 1 square; etching the fourth dielectric layer to form a plurality of openings in the fourth dielectric layer; forming a cap (c) on the semiconductor substrate, and secondly the fourth dielectric layer The layer and the third dielectric layer cover and cover each to remove the delta patterned sacrificial layer. 561131 6. Scope of patent application ___ t ^ Γ Please make the method of the first scope of the patent, which includes a glUe layer formation step before the formation of the Xi ® ^ Cheng Xi ^ layer. The first dielectric layer, the second dielectric layer and: Rong: on a conductor. Said Jiu Jiu's production method of the first case i ί ί i, encircling ί 2 items ′ Wherein when removing the picture and the animal layer, the point landing layer is also removed at the same time. 4. The production method of item 1 in the scope of patent application, straight in the report: with the same ^ ^ ^ ^ ^ t Another 3 has a bloc layer formation step, ^ blind layer in the patterned sacrifice Layer, $ -dielectric layer, the first dielectric layer, and the first conductors. The manufacturing method of step 4 of the method of item 4 in which the barrier layer is also removed when the patterned sacrificial layer is removed. ί. The method of making ΪΠΠΓΓ term ... The third dielectric upper surface is approximately tangent to the figure: υ dioxide layer, υ-oxide layer, and the upper surface of the saponification sacrificial layer. 7. For the production method of item 1 of the scope of the patent application, the method for removing the sacrificial layer in A is to remove the pattern in the ^ 纟 q sentence-seeking wet etching process. 8. If the method of applying for 7 items of patent scope, in which the pattern is removed 561131 6. The scope of the patent application for the sacrifice layer includes an etching step for #etching a plurality of #etch holes in the third dielectric film to uniformly and quickly perform the wet # The patterned sacrificial layer is removed by etching. 9 · The manufacturing method of item 1 in the scope of patent application, wherein the first dielectric layer and the first dielectric layer have a different refractive index, and the third dielectric layer and the fourth dielectric layer also have Different refractive indices. 10. The manufacturing method according to item 1 of the scope of patent application, wherein the first conductor and the first conductor include gold (Au), tungsten (Tungsten, W), copper (Cu), and aluminum (aluminum). , A1), aluminum-copper alloy (A1-Cu al l0y), polycrystalline silicon or other conductive materials. 1 1 · The manufacturing method according to item 1 of the scope of patent application, wherein the material for forming the patterned sacrificial layer includes tungsten (tungsten, W) metal, nitridation> oxidized silica, organic polymer, or porous Shi Xi (p0rous silicon). 1 2 · The manufacturing method according to item 1 of the scope of patent application, wherein the capping layer is an oxide layer. 1 3 · The manufacturing method of item 1 in the scope of the patent application, wherein the openings formed in the fourth layer are a plurality of openings having an equal pitch, an equal width, and an equal depth. Page 19 561131 VI. Scope of patent application 14. A method for fabricating a cantilever beam (Micro-Electromechanical System, MEMS) 'The method includes the following steps: Provide a semiconductor substrate, and the surface of the semiconductor substrate It includes a heavily doped layer and a first dielectric layer; forming at least two first electrodes in the first dielectric layer that reach the surface of the heavily doped layer; the first electrodes between edges and the first electrodes; An optical waveguide line is formed in a dielectric layer, and the optical waveguide line does not contact the surface of the heavily doped layer. A patterned sacrificial layer is formed on the semiconductor substrate and covers the optical waveguide line and the first dielectric layer. An electrical layer and each of the first electrodes; forming an arm layer on the semiconductor substrate and covering the patterned sacrificial layer; forming at least two unpatterned patterned layers in the arm layer Sacrificial layer second electrodes, and each of the second electrodes is respectively located above the first electrodes on the two sides of the light wave; the line-guard two forms a second dielectric in the arm layer And the second dielectric does not contact the surface of the patterned sacrificial layer; the second dielectric layer is etched to form an optical grating in the second dielectric layer; a cover is formed on the semiconductor substrate (Cap) layer, and covering the second electrodes, the second dielectric layer, and the grating; and μ, the patterned sacrificial layer is etched to form a cavity under the arm layer. -hole 561131 VI. Application scope of patent 15. The manufacturing method of item 14 of the scope of patent application, wherein before the sacrifice layer is applied, a glue layer is formed to form the glue layer on the first dielectric layer, The optical waveguide line and above the pole. This step is formed to shape the first electrical 16. The manufacturing method of item 15 in the scope of patent application, wherein the adhesive layer is also removed when the sacrificial layer is applied. 1 7 · The manufacturing method according to item 14 of the scope of patent application, further comprising forming a blocking layer after the sacrificial layer is formed ^ forming the blocking layer on the patterned sacrificial layer, the first dielectric Layer wires and the first electrodes. 18 · The method for manufacturing item 17 in the scope of patent application, wherein the barrier layer is also removed when the sacrificial layer is applied. 19 · The production method according to item 14 of the scope of patent application, wherein the = contains two anchor layers and an oxide layer, and the upper surface of the 苴 ° layer is approximately covered with the patterned sacrificial tritium layer. The patterned sacrificial layer and the fixing method, such as the line 14 of the patent application scope, the arm layer, and the capping layer method, wherein the-is formed by removing the figure by the oxide to form the figure In this step, the arms are aligned with the fixed column by the light wave, and the oxygen optical waveguide is formed. 561131 VI. Application method for patent application range 2 1 · f Patent application range item 14 Production method, wherein the first dielectric layer and the optical waveguide have different refractive indices, and the arm layer and the second dielectric The layers also have different refractive indices. The manufacturing method of item 4 in the scope of the patent application, wherein the first electrode and the second electrode include gold (AU), tungsten (tungsten, w), copper (copper, Cu), Shao (aiuminum, Ai), Ming copper alloy (Al-Cu a 1 1 oy), polycrystalline silicon or other conductive materials. ϋ I ί The manufacturing method of item 14 in the patent scope, wherein the material forming the pattern includes tungsten (tungsten, W) metal, silicon nitride, a lactite, organic polymer, or porous Si i lc. n). Including the mouth, opening the grid, etc. The light should be 1 ^ —, the mouth, the opening method should be the sum of the deep system. To touch the 14th level and the wide range, the distance between the sacrifice and the sacrifice of specialization, please wait for the case to apply for a picture. Page 22 561131 VI. Patent application scope The patterned sacrificial layer is etched. liEHil Page 23